It's not very complicated to import the QUIC library, or to import the HTTP library with HTTP/3 supported. For the library authors, QUIC isn't more complicated to implement than TCP. Doomsaying about the complexity of Google Sheets is completely unrelated to whether QUIC is good tech and superior to TCP, which it is; the only remaining complaint is that it's too new to have been part of the kernel yet, and if that makes technology somehow illegitimate then I guess we're just stuck with the mistakes of the 90s forever, why ever invent anything new at all.